KNEE Flashcards
JOINTS
Tibiofemoral Joint
Patellofemoral Joint
Osteokinematics & normal AROM Values: Knee Flexion
140°
Osteokinematics & normal AROM Values: Knee Extension
0-10° of hyperextension
Arthrokinematics of knee extension: Open Chain
The concave tibia moves on the convex femur.
Anterior roll & Anterior Glide
Arthrokinematics of knee extension: Closed Chain
The convex femur on the concave tibia.
Anterior Roll & Posterior Glide
Ligaments of the knee: (5)
Patella Ligament
Medial collateral ligament
Lateral Collateral ligament
Anterior cruciate ligament
Posterior cruciate ligament
Ligaments & Their Functions: Patella Ligament
Connects patella to tibial tuberosity.
Transmits forces produced by the quadriceps to the tibia
Ligaments & Their Functions: Medial Collateral Ligament
Strong, flat band that connects the medial epicondyle of the femur to the medial meniscus and the medial tibial condyle.
Resists VARUS stress at the knee.
Ligaments & Their Functions: Lateral Collateral Ligament
Strong, cord like.
Connects lateral epicondyle of the femur to the lateral surface of the fibular head.
Resists VARUS stress on the knee
Ligaments & Their Functions: Anterior Cruciate Ligament
Connects the anterior/medial aspect of the tibia to the posterior & medial portion of the lateral condyle of the Femur.
Runs superiorly, posteriorly and laterally (APLS).
Prevents anterior translation of the tibia on the femur, and is the weaker of the two cruciate ligaments.
Ligaments & Their Functions: Posterior Cruciate Ligament
Connects the posterior intercondylar area of the tibia to the lateral portion of the medial condyle of the femur.
Runs superiorly, anteriorly and medially (PAMS).
Prevents posterior translation of the tibia on the femur, and is stronger of the two cruciate ligaments.
Meniscus
Crescent shaped fibrocartilage on the knee.
Deepens articular surface bw femur and tibia.
Wedge shaped to play a role in shock absorption at the knee joint.
The medial meniscus is firmly attached to the MCL and is less mobile.
The lateral meniscus is a more complete circle and this allows for it to be more mobile.
Muscles acting at the Knee and their primary action at the knee: (7)
Hamstrings
Quads
Sartorius
Gracilis
Gastrocnemius
Plantaris
Popliteus
Muscles acting at the Knee and their primary action at the knee: Hamstrings
Semitendinosus, Semimbembrinosus, Biceps Femoris)
Knee Flexion
Muscles acting at the Knee and their primary action at the knee: Quads
Rectus Femoris, Vastus Lateralis, Vastus Medialis, Vastus Intermedius
Knee Extension
Screw Home Mechanism:
Locking knee in full extension requires 10° of external rotation of the tibia.
This can be observed during the final 30° of knee extension.
This rotation cannot be performed independently from knee extension/flexion.
The 10° of external rotation involved helps to improve stability.
The factors influencing this mechanism are:
A) The shape of the medial femoral condyle
B) Tension in the ACL
C) The lateral pull of the quadriceps during active knee extension.
The screw home mechanism is reversed when starting in full extension and can be observed during the first 30° of knee flexion.
Muscles rotate on the Femur Externally to initiate Femoral on Tibial Flexion
Muscles rotate on the Tibia Internally to initiate Tibial on Femoral Flexion
Screw home rotation described as conjuct rotation, meaning that is mechanically coupled to flexion & extension kinematics & cannot be performed independently.
Screw home adds STABILITY & CONGRUENCY of bone-on-bone contact bw femur & Tibia.
